Dam releases could force Mont. flooding downstream

Mitch Anderson, left, hands a sandbag to neighbor Tim Reed as they try to divert floodwaters coursing around Anderson's house in Joliet, Mont., Wednesday May 25, 2011. About a foot of water from the Rock Creek and Red Lodge Creek rushed through the streets of Joliet on Wednesday, about 100 of the a

/ AP

Mitch Anderson, left, hands a sandbag to neighbor Tim Reed as they try to divert floodwaters coursing around Anderson's house in Joliet, Mont., Wednesday May 25, 2011. About a foot of water from the Rock Creek and Red Lodge Creek rushed through the streets of Joliet on Wednesday, about 100 of the about 300 houses in the town have taken in water in their basements or lower levels. (AP Photo/Matthew Brown)

Mitch Anderson, left, hands a sandbag to neighbor Tim Reed as they try to divert floodwaters coursing around Anderson's house in Joliet, Mont., Wednesday May 25, 2011. About a foot of water from the Rock Creek and Red Lodge Creek rushed through the streets of Joliet on Wednesday, about 100 of the about 300 houses in the town have taken in water in their basements or lower levels. (AP Photo/Matthew Brown) (/ AP)

MATTHEW BROWN, Associated Press

As flooding washes out roads and swamps more homes in Montana, regional rains are forcing releases from dams that promise to swell the Missouri River past its banks downstream in Iowa and the Dakotas.

The central Montana town of Roundup was under an estimated 6 feet of water Thursday as the latest bout of flooding pounded the water-logged state.

Melting snow pouring out of the mountains is combining with record rains to cause flooding that officials worry could be the worst in decades.

By Thursday, roads and highways were being closed in many parts of Montana as dozens of rivers and streams overflowed their banks. Authorities declared flood emergencies in three more counties.

The U.S. Army Corps of Engineers predicted hundreds of homes in downstream states could flood as the water flows eastward toward North Dakota.